--- title: "CS ADR-DSN.H.405 – CS ADR-DSN.H.460: CHAPTER H — OBSTACLE LIMITATION SURFACES (Certification Specifications and Guidance Material for Aerodrome Design (CS-ADR-DSN) — Issue 7, Aerodromes) — rule index · Avioverse" description: "CS ADR-DSN.H.405 – CS ADR-DSN.H.460, Regulation (EU) No 139/2014. Applicability: The purpose of the obstacle limitation surfaces is to define the…" url: "https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces" --- # CHAPTER H — OBSTACLE LIMITATION SURFACES Certification Specifications and Guidance Material for Aerodrome Design (CS-ADR-DSN) — Issue 7 · Aerodromes · Regulation (EU) No 139/2014 · CS ADR-DSN.H.405 – CS ADR-DSN.H.460 On this page 1. ## [CS ADR-DSN.H.405 Applicability](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-405) Applicability: The purpose of the obstacle limitation surfaces is to define the airspace around aerodromes to be maintained free from obstacles so as to… 2. ## [GM1 ADR-DSN.H.405 Applicability](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-405) The obstacle limitation surfaces define the limits to which objects may project into the airspace. 3. ## [CS ADR-DSN.H.410 Outer horizontal surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-410) intentionally left blank 4. ## [GM1 ADR-DSN.H.410 Outer horizontal surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-410) The outer horizontal surface should extend from the periphery of the conical surface as shown in Figure GM-H-1. 5. ## [CS ADR-DSN.H.415 Conical surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-415) Applicability: The purpose of the conical surface is to facilitate safe visual manoeuvring in the vicinity of the aerodrome. 6. ## [GM1 ADR-DSN.H.415 Conical surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-415) intentionally left blank 7. ## [CS ADR-DSN.H.420 Inner horizontal surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-420) Applicability: The purpose of the inner horizontal surface is to protect airspace for visual manoeuvring prior to landing. 8. ## [GM1 ADR-DSN.H.420 Inner horizontal surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-420) The shape of the inner horizontal surface need not necessarily be circular. 9. ## [CS ADR-DSN.H.425 Approach surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-425) Applicability: The purpose of the approach surface is to protect an aircraft during the final approach to the runway by defining the area that should be… 10. ## [GM1 ADR-DSN.H.425 Approach surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-425) intentionally left blank 11. ## [CS ADR-DSN.H.430 Transitional surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-430) Applicability: The purpose of the transitional surface is to define the limit of the area available for buildings, other structures or natural… 12. ## [GM1 ADR-DSN.H.430 Transitional surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-430) When the elevation of a point on the lower edge is along the strip and equal to the elevation of the nearest point on the centre line of the runway or… 13. ## [CS ADR-DSN.H.435 Take-off climb surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-435) Applicability: The purpose of the take-off climb surface is to protect an aircraft on take-off and during climb-out. 14. ## [GM1 ADR-DSN.H.435 Take-off climb surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-435) intentionally left blank 15. ## [CS ADR-DSN.H.440 Slewed take-off climb surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-440) intentionally left blank 16. ## [GM1 ADR-DSN.H.440 Slewed take-off climb surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-440) The edge of a Take-off climb surface may be slewed in the direction of a turn away from the extended runway centre line up to a maximum of 15° splay. 17. ## [CS ADR-DSN.H.445 Obstacle-free zone (OFZ)](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-445) An OFZ is intended to protect aeroplanes from fixed and mobile obstacles during Category II and III operations when approaches are continued below… 18. ## [GM1 ADR-DSN.H.445 Obstacle-free zone (OFZ)](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-445) intentionally left blank \[Issue: ADR-DSN/3] 19. ## [CS ADR-DSN.H.450 Inner approach surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-450) Applicability: The purpose of the inner approach surface is to protect final precision approaches. 20. ## [GM1 ADR-DSN.H.450 Inner approach surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-450) intentionally left blank 21. ## [CS ADR-DSN.H.455 Inner transitional surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-455) Applicability: The purpose of the inner transitional surface is to protect aeroplanes during precision approaches and balked landing. 22. ## [GM1 ADR-DSN.H.455 Inner transitional surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-455) It is intended that the inner transitional surface be the controlling obstacle limitation surface for navigation aids, aircraft, and other vehicles that… 23. ## [CS ADR-DSN.H.460 Balked landing surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/cs-adr-dsn-h-460) Applicability: The purpose of the balked landing surface is to protect balked landing. 24. ## [GM1 ADR-DSN.H.460 Balked landing surface](https://avioverse.aero/regulations/easa/aerodromes/cs-adr-dsn/chapter-h-obstacle-limitation-surfaces/gm1-adr-dsn-h-460) intentionally left blank Consolidated from the EASA Easy Access Rules (revision 13 Mar 2026, extracted 13 Oct 2026) for convenience. 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